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Frontiers in Bioscience (Landmark... Jan 2009The balance between production and clearance of reactive species is essential for cell survival. Antioxidant cellular systems evolved to maintain a redox homeostasis... (Review)
Review
The balance between production and clearance of reactive species is essential for cell survival. Antioxidant cellular systems evolved to maintain a redox homeostasis under different physiological and pathological conditions. Therefore, many authors aim at better understanding the mechanisms and functions of cellular antioxidant components and their relationships between each other and with more general cell functions. Nonetheless, the definition of an "antioxidant system" is a wide and sometimes relative concept, and there is no consensus regarding the necessary requisites for classifying a cell functional component into such category. Here, we suggest a list of human antioxidant genes comprehending all gene products fulfilling specific inclusion criteria, such as antioxidant enzymatic function, participation in redox reactions and other molecular interactions directly related to antioxidant activity. The criteria are discussed and the gene-protein-substrate associations between the components of the list are presented. In addition, at http://www.ufrgs.br/icbs/hag we provide a network-based model of human antioxidant genes, which can be used as reference tool to access several database resources (e.g., RefSeq, Ensembl, HGNC and the NCBI Entrez database).
Topics: Antioxidants; Humans; Oxidation-Reduction; Peroxidase; Sulfhydryl Compounds; Superoxide Dismutase
PubMed: 19273363
DOI: 10.2741/3541 -
The Cochrane Database of Systematic... Oct 2006L-cysteine is thought to be a conditionally essential (i.e., essential under certain conditions) amino acid for neonates. It is a precursor of glutathione, an... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
L-cysteine is thought to be a conditionally essential (i.e., essential under certain conditions) amino acid for neonates. It is a precursor of glutathione, an antioxidant that may reduce oxidation injury. The addition of cysteine to parenteral nutrition (PN) allows for the reduction of the amount of methionine in PN, thereby limiting hepatotoxicity, and acidifies the solution, thereby increasing calcium and phosphate solubility, and potentially improving bone mineralization.
OBJECTIVES
To determine the effects of supplementing parenteral nutrition with cysteine, cystine or its precursor N-acetylcysteine on neonatal growth and short and long-term outcomes.
SEARCH STRATEGY
The standard search method of the Cochrane Neonatal Review Group was used. MEDLINE (1966-December 2005), EMBASE (1974-December 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2006) and recent abstracts (until December 2005) from the Society for Pediatric Research/American Pediatric Society, Eastern Society for Pediatric Research, and Society for Parenteral and Enteral Nutrition were searched.
SELECTION CRITERIA
All randomized (RCTs) and quasi-randomized trials that examined the effects of cysteine, cystine or N-acetylcysteine supplementation of neonatal PN were reviewed. Predetermined outcome variables included growth, nitrogen retention, mortality, morbidity secondary to oxidation injury, bone accretion, acidosis, liver disease, and cysteine levels.
DATA COLLECTION AND ANALYSIS
The standard methods of the Cochrane Collaboration and its Neonatal Review Group were used. Statistical analysis included relative risk, risk difference, and weighted mean difference (WMD).
MAIN RESULTS
Six trials fulfilled entry criteria. The majority of patients in these trials were preterm. Five small trials evaluated short-term cysteine supplementation of cysteine-free PN. One large multicenter RCT evaluated short-term N-acetylcysteine supplementation of cysteine-containing PN in extremely low birth weight infants (< or = 1000 grams).
PRIMARY OUTCOMES
Growth was not significantly affected by cysteine supplementation (evaluated in one quasi-randomized trial) or by N-acetylcysteine supplementation (evaluated in one RCT). Nitrogen retention was significantly increased by cysteine supplementation (studied in four trials) (WMD 31.8 mg/kg/day, 95% confidence interval +8.2, +55.4, n = 95, including 73 preterm infants).
SECONDARY OUTCOMES
Plasma levels of cysteine were significantly increased by cysteine supplementation but not by N-acetylcysteine supplementation. N-acetylcysteine supplementation did not significantly affect the risks of death by 36 postmenstrual weeks, bronchopulmonary dysplasia (BPD), death or BPD, retinopathy of prematurity (ROP), severe ROP, necrotizing enterocolitis requiring surgery, periventricular leukomalacia, intraventricular hemorrhage (IVH), or severe IVH. No data were available on other outcomes.
AUTHORS' CONCLUSIONS
Available evidence from RCTs shows that routine short-term cysteine chloride supplementation of cysteine-free PN in preterm infants improves nitrogen balance.However, there is insufficient evidence to assess the risks of cysteine supplementation, especially regarding metabolic acidosis, which has been reported during the first two weeks of cysteine chloride administration. Available evidence from a large RCT trial does not support routine N-acetylcysteine supplementation of cysteine-containing PN in extremely low birth weight infants. A large RCT would be required to assess whether routine prolonged cysteine supplementation of cysteine-free PN affects growth and short and long-term neonatal outcomes in very low birth weight infants.
Topics: Acetylcysteine; Cysteine; Cystine; Dietary Supplements; Humans; Infant, Newborn; Infant, Premature; Parenteral Nutrition; Randomized Controlled Trials as Topic
PubMed: 17054219
DOI: 10.1002/14651858.CD004869.pub2 -
Journal of Internal Medicine May 2002Do antioxidant vitamins, in regular food or as food supplements, protect against myocardial infarction and stroke? In this systematic literature review on the effects of... (Review)
Review
Do antioxidant vitamins, in regular food or as food supplements, protect against myocardial infarction and stroke? In this systematic literature review on the effects of antioxidant vitamins in the primary prevention of cardiovascular disorders, studies with ischaemic heart disease, stroke or combined cardiovascular events as end-points have been included. Studies on the effects of antioxidant vitamins on intermediary end-points (such as blood lipids and blood pressure) and as secondary prevention in patients with manifest cardiovascular disease are reviewed in a conventional manner. In observational studies (case-control or cohort design), people with high intake of antioxidant vitamins by regular diet or as food supplements generally have a lower risk of myocardial infarction and stroke than people who are low-consumers of antioxidant vitamins. The associations in observation studies have been shown for carotene, ascorbic acid as well as tocopherol. In randomized controlled trials, however, antioxidant vitamins as food supplements have no beneficial effects in the primary prevention of myocardial infarction and stroke. Serious adverse events have been reported. After an initial enthusiasm for antioxidants in the secondary prevention of cardiovascular disease, recent reports from of several large randomized trials have failed to show any beneficial effects. Thus, the apparent beneficial results of high intake of antioxidant vitamins reported in observational studies have not been confirmed in large randomized trials. The discrepancy between different types of studies is probably explained by the fact that supplement use is a component in a cluster of healthy behaviour. Antioxidant vitamins as food supplements cannot be recommended in the primary or secondary prevention against cardiovascular disease.
Topics: Antioxidants; Cardiovascular Diseases; Case-Control Studies; Dietary Supplements; Humans; Lipid Peroxidation; Randomized Controlled Trials as Topic; Vitamins
PubMed: 11982737
DOI: 10.1046/j.1365-2796.2002.00973.x